As the respiration rate rises in fruits and tubers treated with ethylene, the absolute level of adenine nucleotides increases markedly. It is intended to examine this phenomenon quantitatively in conjunction with a study of energy-charge states as a function of the respiratory response to ethylene. We propose as well to investigate the basis of the synergism between ethylene and elevated oxygen tensions in the evocation of the respiratory climacteric and its metabolic concomitants. Evidence in hand indicates the need for high oxygen levels is not to sustain respiration. We wish to know whether ethylene and high oxygen levels is not to sustain respiration. We wish to know whether ethylene and high oxygen are responsible for the appearance of peroxide and/or its congeners which are seemingly implicated in the development of the climacteric in fruits, and its counterpart, the pseudo-climacteric, in bulky storage organs. In this context we plan to examine the effect of a variety of anti-oxidants on the development of the induced respiration. Studies will be continued on the genesis and development of cyanide resistant electron transport in selected plant tissues. We have discovered that the respiration of thin fresh storage organ slices, initially cyanide sensitive, becomes cyanide resistant (and hydroxamate sensitive) when aged in actinomycin, for example, a condition under which there is no increase in respiration rate. At the same time the tissue develops a capacity for substrate absorption (e.g. glucose, citrate) previously lacking. It is proposed to investigate the basis of this profound change which takes place in the absence of any new message biosynthesis, and to compare respiratory regulatory controls in such tissue with those in freshly cut slices.